It is known to utilize a beam splitter when one wishes to view two or more identical images. One use of a beam splitter in the art of photography presents an identical image to three image planes to create a color photograph. This use is illustrated in U.S. Pat. No. 1,319,292 which issued Oct. 21, 1919, by W. H. Kunz. The Kunz patent discloses the concept of forming some of the reflective surfaces within the beam splitter as partially reflective surfaces, while the final surface is wholly reflective. The patent fails to disclose a need for identical path lengths between the lens and the image planes, however. In a second patent, U.S. Pat. No. 1,320,625, issued Nov. 4, 1919, by W. H. Kunz, the concept of equal path lengths between the lens and the image planes is disclosed. The second Kunz patent also discloses a fourth beam splitter for a color camera.
The further utilization of a beam splitter may be found in U.S. Pat. No. 3,017,454, issued Jan. 16, 1962, by I. J. P. James, et at. This patent is noteworthy as it shows a color television camera which incorporates a beam splitting configuration with three reflective surfaces for directing a common image toward three pick-up tubes where the optical path length between the lens and each tube is a substantially equal distance. A beam splitter wherein each prism within the splitter reflects a different percentage of the light, may be found in U.S. Pat. No. 4,099,841, issued July 11, 1978, by S. M. Ellis.
From the foregoing, it will be seen that the utilization of a beam splitter to provide identical images at several image planes is known.
The next development step in the prior art was to place a plurality of photosensors or photodetectors at the image plane to detect the image. Such photosensors may include charge coupled devices (CCD), charged injection devices (CID), or the like. One such arrangement utilizing a beam splitter and photosensors may be found in U.S. Pat. No. 4,005,285, issued Jan. 25, 1977, by E. E. Price. This patent teaches a device for improving the resolution of an image by utilizing a beam splitter to optically compact the photosensors in a continuous image line. However, this device does not provide for the rapid, two dimensional image of a two dimensional display as the device is limited to a linear arrangement. A second linear array that also improves resolution may be found in U.S. Pat. No. 4,009,388, issued Feb. 22, 1977, by N. J. Seachman.
A prior art patent utilizing a beam splitter that reports to produce a two dimensional display may be found in U.S. Pat. No. 4,053,773 which issued Oct. 11, 1977, by B. A. Deresh, et al. While this patent discusses a two dimensional display, it must be noted that the patent is limited by the physical size of the photosensor or the photodetector array. That is, the largest dimensions of the two dimensional display to be formed by the Deresh, et al. invention are limited by the size of array that one can fabricate.